Packet analyzers (also known as protocol analyzer) are computer programs that can intercept and log traffic passing over a digital network or part of a network. These are very handy tool in web development & analytics as they can do post-mortem of all your Request & Response and provide you a detail information while interacting with web server. You can capture all information like request & response headers, request size, errors/warnings, response codes, response time, cookies, query strings and so on.

Below are some of good browser specific Packet analyzers that can assist you in web development and make you life pretty simple.